I followed the tutorial and found some missing infos and I did some errors too. I use tomcat 4.1 and modified the code to link to a MS Access database on Windows XP.
1)
Missing in web.xml in this tutorial:
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/servlet/login</url-pattern>
</servlet-mapping>

and if you do this:
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/servlet/*</url-pattern>
</servlet-mapping>

All URL containing /servlet/ will be redirect to the login class!!!

2) Recheck your typo, I wrote WEB_INF instead on WEB-INF! Lost a half day why a having a 404 page!